| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
We showed previously that Epstein-Barr virus (EBV) latency is disrupted and the virus-replicative cycle is activated after ecpression of EBNA2 in the Burkitt's lymphoma-derived Akata ells. It was also shown that EBNA2 suppresses proliferation and induces cell death in Akata cells. In this project, the following new findings have been obtained by gene transfer experiments with a tetracycline-regulated EBNA2 expression vector.
1. Involvement of RBP-J κ in EBV activation by EBNA2
Analysis of the functions of an EBNA2 deletion mutant, EBNA2 (del.248-382), indicated that the domain responsible for binding to RBP-J κ is necessary for EBNA2's ability to disrupt EBV latency in Akata cells.
2. Induction of CD40 by EBNA2
At 2-3 days after induction of EBNA2 in Akata cells, a population of cells with marked CD40 expression was recognized by flow cytometry. This CD40 induction was not observed in EBV-negative Akata cells, suggesting that EBV genes transactivated by EBNA2 mediate this function of EBNA2.
3. Reduction of surface IgG expression by EBNA2
At 2-3 days after induction of EBNA2 in Akata cells, the level of surface IgG expression, as revealed by flow cytometry, was downregulated. This effect of EBNA2 was recognized both EBV-positive and -negative Akata cells, suggesting the it is a direct effect of EBNA2.
4. Reduction of c-Myc expression by EBNA2
At 1-2 days after induction of EBNA2 in Akata cells, c-Myc level, as assessed by western blot analysis, was markedly suppressed. Since c-Myc over-expression, resulting from chromosomal translocation, has critical role in the proliferation of Burkitt's lymphoma cells, this reduction in c-Myc expression is likely to be important in EBNA2-mediated growth suppression of Akata cells.
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